This disclosure relates generally to projection systems, especially multiple projector systems that project multiple video images to a common display location, such as a screen or wall. These systems can be configured to allow multiple component images to overlap completely, not at all, or anything in between. For example, the multiple component images can overlap completely to produce a single composite image (e.g. to provide greater luminance, resolution, etc.), or the component images can be tiled together, edge-to-edge, with little or no overlap, to produce a composite image made up of several discrete component images.
There are a variety of methods that allow multiple video images to be blended in a single video display, but most of these involve video processing that is performed at the origin of the video signal, rather than at the projection end. One common method for producing composite images and creating the appropriate masks is chroma key (aka “bluescreen” or “greenscreen”) processing. Chroma key processing produces a single composite image in which a real object appears to be positioned in front of a virtual background image that has been segmented into the video signal. Perhaps the most well known example of the use of chroma key systems is that of a television weatherman standing in front of a computer-generated weather map, explaining the weather.
In a chroma key system the mask for combining multiple video images is created at the image source—i.e. by the image processors associated with the cameras or other systems that create the individual component images. However, in a multiple projection system it can be desirable to send multiple individual video signals to separate projector systems that are configured to mask and blend the multiple images into a single display at the projection end.